diff --git a/validators/number.test.ts b/validators/number.test.ts
index e5ba370..2ed6de1 100644
--- a/validators/number.test.ts
+++ b/validators/number.test.ts
@@ -7,6 +7,8 @@ import {
 
 Deno.test("isNumber (match)", async () => {
   const values = [
+    undefined,
+    null,
     0,
     1,
     2e64,
@@ -21,8 +23,6 @@ Deno.test("isNumber (match)", async () => {
 
 Deno.test("isNumber (no match)", async () => {
   const values = [
-    undefined,
-    null,
     NaN,
     "0",
     true,
@@ -39,6 +39,8 @@ Deno.test("isNumber (no match)", async () => {
 
 Deno.test("isInteger (match)", async () => {
   const values = [
+    undefined,
+    null,
     0,
     1,
     2e64,
@@ -51,8 +53,6 @@ Deno.test("isInteger (match)", async () => {
 
 Deno.test("isInteger (no match)", async () => {
   const values = [
-    undefined,
-    null,
     NaN,
     "0",
     true,
diff --git a/validators/number.ts b/validators/number.ts
index 9fd57e8..c53acaf 100644
--- a/validators/number.ts
+++ b/validators/number.ts
@@ -3,6 +3,7 @@ import { Validator, Args } from "../mod.ts";
 export const isNumber: Validator = {
   type: "isNumber",
   check: (value: any) => {
+    if (value === null || value === undefined) return;
     if (!Number.isFinite(value)) {
       return {};
     }
@@ -15,6 +16,7 @@ export const isNumber: Validator = {
 export const isInteger: Validator = {
   type: "isInteger",
   check: (value: any) => {
+    if (value === null || value === undefined) return;
     if (!Number.isInteger(value)) {
       return {};
     }
diff --git a/validators/string.test.ts b/validators/string.test.ts
index 0776460..23ba2a5 100644
--- a/validators/string.test.ts
+++ b/validators/string.test.ts
@@ -7,6 +7,8 @@ import {
 
 Deno.test("isString (match)", async () => {
   const values = [
+    undefined,
+    null,
     "",
     "foo",
     new String(),
@@ -19,8 +21,6 @@ Deno.test("isString (match)", async () => {
 
 Deno.test("isString (no match)", async () => {
   const values = [
-    undefined,
-    null,
     0,
     1,
     true,
diff --git a/validators/string.ts b/validators/string.ts
index 89cedbe..3d84c3d 100644
--- a/validators/string.ts
+++ b/validators/string.ts
@@ -3,6 +3,7 @@ import { Validator, Args } from "../mod.ts";
 export const isString: Validator = {
   type: "isString",
   check: (value: any) => {
+    if (value === null || value === undefined) return;
     if (typeof value !== "string" && !(value instanceof String)) {
       return {};
     }